1. Field of the Invention
The present invention relates generally to a system and method of enabling a network that uses radio frequency (RF) communication to have multiple host connections on diverse nodes within a home network and/or within a complementary network. More particularly, the present invention relates to a system and method of automatically routing messages to an accessible connection in the event of a failure such that the redundant host connection can either be active all the time (e.g., round-robin between available connections) and/or configured as a hot standby (e.g., routed to backup when the primary host computer and/or routing node associated therewith is down), and optionally utilizing a backup queue manager in the event that the primary queue manager is unavailable for any reason.
2. Background Description
FIGS. 1–3 show a prior art radio frequency (RF) transmission system 100, as disclosed in U.S. Pat. No. 5,819,172, incorporated herein by reference, for transmitting information from one of a plurality of originating processors A–N to at least one of a plurality of destination processors (A–N) which may be transported during operation. The system 100 includes: at least one gateway switch 150 that stores information received from one of the at least one originating processor prior to transmission of the information to the at least one destination processor; a RF information transmission network 130 for transmitting stored information received from one of the at least one gateway switch 150 by RF transmission to at least one destination processor; and at least one interface switch 162 that connects a gateway switch 150 to the RF transmission network 130 and transmits stored information received from one of the at least one gateway switch 150 to the RF information transmission network 130.
The information is transmitted to a receiving interface switch by the electronic mail system in response to an address of the receiving interface switch which has been added to the information originated by the originating processor by either the originating processor or gateway switch 150. The information is transmitted from the receiving interface switch to the RF information transmission network 130 with an address of the destination processor to receive the information which has been added by either the originating processor, a gateway switch or the receiving interface switch.
More particularly, FIG. 2 illustrates a block diagram of the connection between a plurality of gateway switches with mailboxes 150 in different electronic mail systems to the RF information transmission network 130. Multiple gateway switches with mailboxes 150 from a single electronic mail system 1–N may be connected to each interface switch 162 instead of the connection of a single gateway switch with a mailbox to a single interface switch as illustrated. A plurality of interface switches 162 connect information transmitted from at least one electronic mail system as illustrated in FIG. 1. Optionally, a plurality of electronic mail systems 1–N are connected to a data input port of the RF information transmission system which is preferably hub switch 116. The dotted line communication paths 163 illustrate optional information transmissions in which information from a plurality of different electronic mail systems is concentrated at a single interface switch as illustrated in FIG. 2. The dotted line communication paths 163 illustrate connections to additional gateway switches with mailboxes 150 within electronic mail systems 1–N.
The interface switches 162 function as a security check to determine that information transmissions originating from a gateway switch with mailbox 150 represent transmissions which should be coupled to a hub switch 116 of the RF information transmission network 130. The security check is performed by the interface switch 162 comparing the identification number of the RF receiver 119 which has been added by either an originating processor A–N or a gateway switch with mailboxes 150 with permissible identification numbers or the interface switch performing the addition of the identification number.
The interface switch 162 also removes information added by the electronic mail system 1–N to the information originated by the originating processor A–N from the stored information received from one of the gateway switches 150, and adds information used by the RF information transmission network 130 during transmission of the information originated at the originating processor to a RF receiver 119 in the RF information transmission network 130 which receives the information and transfers it to the destination processor A–N. Additionally, the interface switch 162 encodes data, which is required to format the display of the cathode ray tube (CRT) of the destination processor for the electronic mail system to which the destination processor is connected, in the form of a character or characters which are decoded by either the RF receiver 119 or the destination processor A–N. This information is added in decoded form back to the information which is processed by the destination processor with a format of the electronic mail system to which the destination processor A–N is connected.
The interface switches 162 also function to store information which has been stored by at least one gateway switch 150 that is received from a plurality of originating processors, and assemble the information from a plurality of originating processors into a packet having a predetermined format and transmit the packet to the hub switch 116 within the RF information transmission network 130. The hub switch is the preferable node in the RF information transmission network to which communications from the gateway switches 150 should be transmitted as a consequence of it having jurisdiction over both local access and transport area (LATA) switches 114 and the local switches 112 in the RF information transmission network, which results in lesser network overhead.
The hub switch 116 receives the packet from the receiving interface switch 162 and disassembles the packet into information from the plurality of originating processors. The originating processors are either within a single electronic mail system such as system 100, or from a plurality of electronic mail systems, such as systems 1–N, or from outside of any electronic mail system from at least one additional processor 312 which is connected directly to interface switch 162 to originate information to be transmitted to a destination processor A–N in an electronic mail system as described below. The RF information transmission network 130 transmits the disassembled information from the hub switch 116, including the identification number of the RF receiver 119 transferring information, to the destination processor A–N to a local switch 112 storing the file identified by the identification number and any destination of the RF receiver in the RF information transmission network to which the information and identification number is to be transmitted by the RF information transmission network, and adds any destination of the RF receiver to the information. The RF information transmission network, in response to any added destination, transmits the information and identification number to the destination for RF broadcast to the RF receiver 119 for transfer to the destination processor A–N.
The information is transmitted to a receiving interface switch 162 from one or more gateway switches 150 by one or more electronic mail systems 1–N in response to an address of the receiving interface switch which has been added to the information originated by the originating processor by either the originating processor or gateway switch. The information is transmitted from the receiving interface switch 162 to the RF information transmission network with an address of the destination processor, such as a name of a user of the destination processor A–N, to receive the information which has been added by either the originating processor A–N, a gateway switch 150 or the receiving interface switch 162.
Preferably, the address of the receiving interface switch is a code word, such as “TF-MOBOX”, which is recognized throughout the electronic mail system when appended to information as directing the information to be transmitted to the interface switch 162. The address of the destination processor is preferably the identification number of the RF receiver 119 within the RF information transmission network 130. The address of the receiving interface switch may be added to the information originated by the originating processor, by a gateway switch 150 or by the originating processor A–N. The address of the receiving interface switch 162 may be added to the information by matching an identification of the destination processor A–N which may be the name of the individual utilizing the processor or some other information to add an address of an interface switch such as the aforementioned “TF-MOBOX” stored with the matched identification of the destination processor to the information as the address of the receiving interface switch.
Alternatively, the originating processor may be used to add the address of the receiving interface switch 162 by inputting the address of the receiving interface switch (TF-MOBOX) along with an identification of the destination processor A–N (name of recipient using the processor).
The originating processor A–N may also add the address of the receiving interface switch 162 by matching an identification of the destination processor (name of the user of the processor) with a stored identification of a destination processor and adding an address of the interface switch (TF-MOBOX) stored with the matched identification of the destination processor to the information as the address of the receiving interface switch.
The identification number may be added to the information originated by the originating processor or, alternatively, maybe added by the originating processor by matching an identification of the destination processor (the name of the user of the processor) with a stored identification of a destination processor (the authorized user of the destination processor) and adding an identification number stored with the matched identification of the destination processor to the information as the identification number of the RF receiver 119. Alternatively, the aforementioned matching process may be performed by either the gateway switch 150 or the interface switch 162. The additional processors 312 originates information from outside of any electronic mail system.
Processors 312 provide an address of at least one destination processor in an electronic mail system, such as the name of the user, to receive information transmitted by the RF information transmission system 130, or an identification number of the RF receiver 119 receiving information and transferring the information to the destination processor. The interface switch 162 which receives the information from each processor 312 adds information used by the RF information transmission network 130 during transmission of the information to the RF receiver 119 receiving the information in the same manner as described above with respect to the interface switch 162.
Processors 312 are only required to have a telephone modem and support programming to format information for RF transmission to a destination processor A–N within any one of one or more electronic mail systems 1–N. The processors 312 are not required to have the necessary electronic mail system software present in originating processors A–N or interconnections with an electronic mail system. As a result of the connection to the interface switch 162, information originating from the additional processors 312 may be transmitted by RF transmission to a destination processor A–N within any one or a plurality of electronic mail systems with the user of the processor 312, the processor 312 or the interface switch 162 only having to supply an identification number of the receiver 119 to input information into the RF information transmission system 130 for RF transmission to a destination processor.
The difference between originating information by one of the additional processors 312 outside of any electronic mail system and originating information by one of the processors within one of the electronic mail systems is that the direct connection of the additional processor to the interface switch 162 eliminates the requirement for the adding of an address of the interface switch 162 which is required by the electronic mail systems to forward the information to the interface switch where necessary formatting of the information to be compatible with the RF information transmission system is performed. The interface switch 162 packetizes information originating from the additional processors 312 in the same manner as described above with respect to information originating from within an electronic mail system.
Information from within an electronic mail system and originating from additional processors 312 outside of the electronic mail system may be formatted into the same packets which are forwarded to the hub switch 116. Additionally, interface switch 162 may be connected only to the additional processors 312 to provide an interface only for processors outside of any electronic mail system to destination processors A–N within one or more electronic mail systems 1–N. The only information which is necessary to be inputted by the additional processors 312 is the address of the destination processor (user of the processor). The addition of the identification number of the receiver 119 may be added by matching of an identification of the destination processor with stored destination processors within the additional processor 312, or the interface switch 162 with an identification number of the receiver 119 stored with an identification of a destination processor A–N used as an identification of the destination processor upon a match having been made.
U.S. Pat. No. 5,819,172 does not, however, generally relate to, for example, a system and method of enabling a network that uses radio frequency (RF) communication to have multiple host connections on diverse nodes within a home network and/or within a complementary network. Nor does U.S. Pat. No. 5,819,172 relate, for example, to a system and method of automatically routing messages to an accessible connection in the event of a failure such that the redundant host connection can either be active all the time (e.g., round-robin between available connections) and/or configured as a hot standby (e.g., routed to backup only when the primary is down), and optionally utilize a backup queue manager in the event that the primary queue manager is unavailable for any reason.
FIG. 4 is a prior art diagram from U.S. Pat. No. 5,940,771, incorporated herein by reference, which illustrates the basic communication pathways and spatial relationships between a host computer, base stations and roaming terminals. Particularly, a host computer 411 and roaming terminals 413, 415 and 417 indirectly communicate through base stations 419 and 421.
The base stations 419 and 421 receive communications via one link medium and relay those communications along another. Particularly, a “hard-wired” connection such as an IEEE 802.3 (Ethernet) interface provides a link 423 to host computer 411, while radio frequency (RF) transmission provides the link to the roaming terminals 413, 415 and 417.
If the remote terminals 413, 415 and 417 are within the RF range of each other, they can use direct RF transmission as the link. If they are not within RF range, an indirect communication link must be found through the base stations 419 and 421. The RF range of the base stations 419 and 421 is illustrated in FIG. 4 by the respective circular boundaries 425 and 427. The boundaries 425 and 427 represent the maximum radial distance from the base stations 419 and 421 that RF communications can be maintained.
In one preferred embodiment, the host computer 411 can be either an IBM AS400 or 3090 mainframe. The base stations 419 and 421 are NORAND RB4000 products and the roaming terminals 415, 417 and 419 are NORAND RT1100 products.
Although only one host computer, two base stations and three roaming terminals are shown for simplicity, the use of additional host units, many more base stations and hundreds of roaming terminals are contemplated. Instead of the “hard-wired”Ethernet interface, it is also contemplated that the entire link 423, or any portion thereof, can be maintained using RF transmissions. In such situations, because of the range limitations associated with an RF link, it may be necessary for several base stations to relay communications between the host computer 411 and the roaming terminals 413, 415 and 417. Alternatively stated, the communications “hop” from one base station to the next until the destination is reached.
As the number of base stations increase, the number of possible “hopping” pathways also increase. A backward-learning, spanning tree algorithm is used so as to select the “hopping” pathway with the lowest “cost” to a given destination as detailed above. To summarize, a “cost” is assigned to every direct communication link in the network. This “cost” factor takes into account the communication bandwidth of a particular link. Next, the spanning tree algorithm using backward learning identifies the “hopping” pathway of lowest “cost” from any source to any destination. Whenever any direct link is faulty or a “hopping point” (a base station for example) is moved or breaks down, an alternate low “cost” pathway can be used. This provides an inherent redundancy to the network.
Roaming terminals 415, 417 and 419 collect data that must be communicated to the host computer 411. This data is collected either via respective bar code readers 429, 431 and 433 or keyboards 435, 437 and 439. U.S. Pat. Nos. 4,910,794, 4,924,462, and 4,940,974 provide a further description of these readers and data collection, and are incorporated herein by reference. In addition, bar code reading requires high system clock rates in the roaming terminals during data gathering to provide decoding of bar code scans at an acceptable rate. However, the high clock rates also cause the generation of digital noise in and around the roaming terminals. This noise can effect transmission and reception at the roaming terminal causing a reduction in the effective communication range. This problem is solved by using a dual clock rate. The terminal is operated normally at a slow system clock rate to minimize the generation of digital noise, and it is switched to a fast clock rate during bar code scanning to allow the data obtained from the bar code scan to be processed at a higher rate. This lets the RF data link coexist with the need for and the hardware support for bar code scan decoding.
The terminals 413, 415 and 417 can also request information from the host computer 411 or from other roaming terminals. Similarly, the host computer 411 may desire to communicate with the roaming terminals 413, 415 and 417 in order to download configuration information, database information or to send commands.
Before communication can be initially established, the roaming terminals 413, 415 and 417 must first listen for hello-messages from the base stations 419 and 421. The base station 419 and 421 both send out hello-messages approximately once every second. The hello-messages identify the sending base station along with its current loading and associated “cost”.
The roaming terminals 413, 415 and 417 attempt to detect every possible hello-message from any base station within range. This requires that the hello-message listening period be at least as long as the maximum time between hello-messages sent by any single base station. For example, the terminals 413 and 417 would respectively receive a hello-message from the base stations 419 and 421, while the terminal 415 would receive two hello-messages: one from the base stations 419 and one from the station 421. Only those hello-messages that meet a minimum “signal strength” threshold are further considered. All weaker hello-messages are ignored.
As spatially represented in FIG. 4, upon receiving hello-messages from a single base station, the roaming terminals 413 and 417 can immediately initiate communication with the host computer 411 by “attaching” to their respectively identified base stations 419 and 421. The roaming terminal 415, however, which received two sufficiently strong hello-messages signals, must select either base station 419 or 421 before “attaching”.
To make this selection, the roaming terminal 415 must initially consider the “cost”. Specifically, terminal 415 must select the base station which has the lowest “cost”. If the “costs” are equal, terminal 415 must select the base station whose received hello-message has the highest “signal strength”. If the corresponding “signal strengths” also prove to be equal, the roaming terminal 415 selects the base station with the highest user defined “priority”. This priority can be preset by the user based on both the spatial layout and the nature of the components being used. Finally, if these factors all prove equal, the terminal 415 merely selects the base station with the lowest “preset number”. Each base station is randomly assigned a unique “preset number” upon its manufacture or during its installation onto the network.
Assuming that station 419 and 421 have the same “cost” and “signal strength” but that station 419 has the highest user defined “priority”, gravitation in the overlapping region occurs toward the base station 419. In this way, the base station 419 can better regulate communication in the overlapping RF regions with minimal channel contention.
More particularly, the user set “priority” assigned to a base station could also be determined based on the spatial layout of competing base stations. The higher “priority” base stations can be surrounded by lower “priority” base stations and vice versa in a pattern defined by the total area being covered so as to cause as much migration as possible onto the higher “priority” base stations and away from the lower “priority” base stations. Similarly, in determining high “priority”, consideration can also be given to the base stations ordinarily containing high concentration of roaming terminals.
It is further contemplated that factors which indicate the current load on base stations 419 and 421 could also be considered in the selection by the roaming terminal 415. First, if heavy loading is considered a negative factor, the roaming terminals 413, 415 and 417 that pass within the overlapping region defined by boundaries 425 and 427 would gravitate toward base stations with the lightest load. Although this balances the loading between base stations, it causes greater channel contention problems in the overlapping regions. Second, if heavy loading is considered a positive factor, the roaming terminals would gravitate toward base stations with the heaviest load. In this manner, a heavily loaded base station could better manage communication when surrounded by lightly loaded stations.
As roaming terminals 413, 415 and 417 move within the confines of boundaries 425 and 427, they often need to re-evaluate their base station selection. Instead of waiting until RF communication with their selected base station is entirely lost, the remote terminals 413, 415 and 417 can periodically re-evaluate the “cost” and “signal strength” of either the hello-messages or any other RF transmission sent from other base stations. Upon selecting a new base station, the roaming terminals merely “attach” to their new selection. Furthermore, in addition to or in place of this periodic re-evaluation described in the preferred embodiment, a decline in the selected base station's “signal strength” might also be used as a factor for initiating a re-evaluation.
In a communication system such as that shown in FIG. 4, one or more of the base stations may be selected to transmit an RTC heartbeat, which is the system synchronizing signal. Responses from terminals in the service area are monitored by all of the base stations that receive signals from the terminals. In most cases, terminals will be at different distances from each of the plurality of base stations, and the resulting differences in received signal strengths at the receiving terminals will eliminate the effects of signal collision by FM capture. However, in some instances, collisions will still occur at some base stations.
Base stations can be networked, as illustrated by communication link 423, to allow the coordination of polling of terminals that have identified themselves to the base stations during their response intervals. The use of information about the strength of signals received at the base stations allows the network to adjust broadcast signal strengths so as to poll receiving terminals simultaneously with a minimum risk of collision. This provides a number of advantages. First, a smaller number of collisions will reduce the number of delays in response due to collisions. If contention polling is used, this means that the number of slots can be reduced, thus reducing overhead. The system also allows for simultaneous communication on a single frequency when two or more terminals are so located with respect to their base stations that the same-frequency communications will not interfere with each other. Finally, the system allows UHF and spread-spectrum communication systems to share the same local-area network.
However, unlike the present invention which is directed to providing a system and method for backup and/or redundant host routing and/or message queuing when wireless device is within a home network and/or a complementary network, the system as described in U.S. Pat. No. 5,940,751 does not allow a wireless device to transmit a message between disparate networks. Moreover, U.S. Pat. No. 5,940,771 does not provide a backup and/or redundant routing path between a wireless device and a destination host. Accordingly, there is a need for a system and method that provides such features.